1. Field of the Invention
The present invention relates to a mechanism for locking and unlocking a headrest for automobile.
2. Description of Prior Art
Normally, a headrest for use with an automotive seat has a pair of headrest stays projecting donwardly therefrom. Via those two headrest stays, the headrest is mounted and supported on the seat back of the automotive seat. In most cases, a pair of headrest holders are utilized to support the respective two headrest stays upon a seat back frame which is provided in the seat back. Each headrest holder is fixed on the top of seat back frame and of a cylindrical shape allowing insertion of the corresponding headrest stay therein. Further, a headrest vertical adjustment mechanism is provided between the headrest stays and headrest holders so that the headrest per se can be adjustably raised and lowered via the headrest holders according to the physique and head position of a user sitting on the seat.
Due to the cylindrical body of the headrest holder, it is possible to forcibly draw and remove the headrest stay therefrom to separate the headrest from the seat back when in no use or whenever required. But, this is not always favorable because it is troublesome to insert the removed headrest or headrest stay in the headrest holder when a user sits on the seat, and, in the case of traffic accident including a collision, a great force generated thereby may draw and separate the headrest or headrest stays away from the headrest holders, resulting in a great damage to the user.
To solve those problems, there has been made available a headrest removal preventive mechanism which can be arranged in one of the two headrest holders and in the corresponding one of the two headrest stays, so as to insure preventing removal of the headrest from the seat back. A typical conventional mode of such headrest removal preventive mechanism basically comprises: a notch formed in the headrest stay; a lock piece provided in the headrest holder fixed on a seat back frame, the lock pieces being provided with a bent contact portion and a pair of springs adapted to bias the lock piece in one direction, with such arrangement that the lock piece may be biasingly engaged in the notch to thereby completely prevent removal of the headrest from the seat back. This sort of headrest removal preventive mechanism is not designed to permit for removal of the headrest, and therefore, in the case where the headrest needs to be removed from the seat back, an unlocking arrangement will be required to release the lock piece of the headrest removal preventive mechanism from the notch formed in the headrest stay. For example, when the seat back with a headrest has to be folded down to transform its rear side into a cargo load floor, it is necessary to remove the headrest from the seat back by the unlocking arrangement. Conventionally, the typical simplified mode of the unlocking arrangement is such that a bore is formed in the headrest holder to communicate with a part of the lock piece provided therein and a suitable tool is inserted in that bore to contact and press the contact portion of the lock piece, overcoming the biasing force of the spring, so as to disengage the lock piece from the notch, thereby allowing a user to remove the headrest from the seat back.
However, such unlocking arrangement has been found defective in that a user must keep holding the tool with one hand to disengage the lock piece from the notch, while holding the headrest with another hand against movement. It is therefore troublesome and uneasy for the user to remove the headrest from the seat back.
In view of the above-stated drawbacks, it is therefore a primary purpose of the present invention to provide an improved locking/unlocking mechanism for headrest, which allows for easy removal of the headrest from a seat back of automotive seat.
In order to attain such purpose, the locking/unlocking mechanism in accordance with the present invention, which is provided in a headrest holder having a through-bore in which a headrest stay is slidably inserted, basically comprises:
a lock element which is so provided as to be movable toward and away from a through-bore of the headrest holder, the lock element including an engagement means and a hole, wherein the lock element is movable between a locking position where the engagement means of lock element is to be engaged with a stopper notch formed in the headrest stay, and an unlocking position where the engagement means is to be disengaged from the stopper notch;
a biasing means for resiliently biasing the lock element in a direction to the locking position; and
an unlocking hole formed in the headrest holder in such a manner as to allow an unlocking tool to be inserted therethrough and engaged with the hole of lock element so as to retain the lock element in the unlocking position.
Accordingly, a user can easily remove the headrest from the headrest holder or the seat back frame, without using his or her one hand to keep holding the unlocking tool.
In one preferred mode, the lock element may be formed with a lock hole therein, so that the headrest stay passes through that lock hole, and the engagement means of lock element may comprise an engagement edge defined in the hole, with such an arrangement that, when a portion of the headrest stay excepting the stopper notch is positioned in the lock hole, the lock element is set in the unlocking position, whereby the engagement edge of lock hole is disengaged from the stopper notch and the unlocking hole is aligned with the hole of lock element, thereby allowing the unlocking tool to be inserted in both of the unlocking hole and hole to retain the lock element in the unlocking position, and that, when the stopper notch of headrest stay is positioned in the lock hole, the lock element is moved to the locking position by the biasing means, whereby the engagement edge of lock hole is engaged in the stopper notch.
In the case where the headrest holder includes a head adapted to be securely mounted upon the seat back frame and a cylindrical body extending downwardly from the head, with the through-bore formed in both of the head and cylindrical body, the lock element and biasing means may be provided within the head of headrest holder, such that the unlocking hole extends through the head toward said lock element.